1. Field of the Invention
The present invention relates to a method of oxidizing a silicon substrate and a method of forming an oxide layer. More particularly, the present invention relates to a method of oxidizing a silicon substrate using a nitrogen gas to thereby form an excellent oxide layer on the substrate, and a method of forming an oxide layer or a metal oxide layer on a substrate.
2. Description of the Related Art
Generally, semiconductor devices include various circuit patterns electrically connected to each other. The semiconductor device may be operated by transmitting electric signals from one circuit pattern to another circuit pattern. As the integration degree of semiconductor devices has increased, the sizes of the circuit patterns may be greatly reduced and the circuit patterns may be highly stacked. That is, as the design rule of semiconductor devices decreases, the size and thickness of the circuit patterns also decrease.
In particular, the reduction of the design rule affects the dimension of a dielectric layer of the semiconductor device. The semiconductor device generally includes several dielectric layers such as a gate dielectric layer and a capacitor dielectric layer. A gate dielectric layer, for example, has a thickness of less than about 1 nm when the semiconductor device has a design rule of below about 100 nm. When the gate dielectric layer of less than about 1 nm is formed on a semiconductor substrate, leakage current may be generated from the gate dielectric layer due to a tunneling effect thereof. Since the leakage current may cause a failure of the semiconductor device, a dielectric layer having high dielectric constant to ensure a sufficient capacitance without the generation of the leakage current is desirable.
Dielectric materials having high dielectric constant, for example, include hafnium oxide (HfO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), rare earth metal oxide, etc. When a dielectric layer is formed using the dielectric material having a high dielectric constant, much leakage current may be generated from the dielectric layer although the dielectric layer may have high dielectric constant.
To reduce the leakage current of the dielectric layer, nitrogen may be incorporated in a metal oxide layer serving as the dielectric layer. Here, nitrogen may be incorporated in the metal oxide layer by nitrification of the metal oxide layer by a rapid thermal nitration (RTN) process or a plasma RTN process after forming the metal oxide layer. An additional annealing process should be performed to incorporate nitrogen into the metal oxide layer in the RTN process and the plasma RTN process. In addition, nitrogen may not be properly incorporated in the metal oxide layer by the RTN process or the plasma RTN process.
Recently, an atomic layer deposition (ALD) process has been widely used to form a thin oxide film having good uniformity on a substrate. According to the ALD process, the oxide film may be formed on the substrate by the atomic unit. There are drawbacks when the oxide layer is formed by the conventional ALD process such as greatly increased time for forming the oxide layer and deteriorated characteristics of the oxide film.